Removal of oxidic impurities for the growth of high purity lead iodide single crystals

Abstract It could be shown that the hydrogen (H 2 ) treatment of lead iodide (PbI 2 ) is capable to effectively reduce oxidic impurities contained in the source material used for single crystal growth. Comparative experiments of melting PbI 2 in H 2 and Ar atmosphere as well as thermal analysis (DTA, DSC/TG) of contaminated PbI 2 were carried out to characterise the influence of the H 2 treatment on the resulting material purity. At the same time, a hygroscopic nature of PbI 2 could be disproved, and new results on the controversially discussed thermal behaviour of solid, oxide-polluted PbI 2 are presented. Effective measures for the avoidance of oxidic impurities during source material processing could be derived. Finally, the effectiveness of an H 2 treatment is confirmed by single crystal growth experiments using the Czochralski technique. PbI 2 crystals with improved structural properties and, for the first time, a reproducible predetermination of crystallographic orientation are shown.